[Cerebellar atrophy in Minamata disease: comparison with spino-cerebellar degeneration on MR images]

We evaluated atrophic patterns of the cerebellar vermis in seven patients with Minamata disease (MD) and nine patients with spino-cerebellar degeneration (SCD) on MR images. Twenty-five control subjects were also examined. The cerebellar vermis was divided into superior, middle, and inferior parts by the primary fissure and the prepyramidal fissure on the median sagittal T1-weighted MR image. The length and area of each part were measured. In the patients with SCD, there were no significant differences in the degree of atrophy among the three parts. However, MR images of the patients with MD showed more severe atrophy in the middle and inferior parts than in the superior part. Atrophy of the superior part was less frequently observed in MD patients.

Demonstration of mercury in the human brain and other organs 17 years after metallic mercury exposure

A male subject became exposed to metallic mercury vapor at work in 1973. He excreted 1,850 mg Hg/l urine initially. Controls of urine mercury excretion after D-penicillamine administration led to the assumption of a total body clearance of mercury latest since 1976. Subsequently he developed an organic psychosyndrome without detectable signs of classical mercurialism. He never returned to work again and died of lung cancer in 1990. In different organs (brain, kidney, and lung) which were sampled at autopsy elevated levels of mercury were documented by atomic absorption analysis. Histological examination of the tissue by the Danscher and Schroder method, which is specific for mercury, showed a highly positive staining in the majority of nerve cells and cells of other organs. Ultrastructurally mercury could be demonstrated by elemental x-ray analysis within lipofuscin deposits. The lipofuscin content was increased in the mercury positive nerve cells as demonstrated by a strong positive autofluorescence.

Increased urinary trypsin-inhibitory activity in mercuric chloride induced nephrotoxicity in Wistar rats

The relationship between trypsin-inhibitory activity (TIA) and the nephrotoxic effects of mercuric chloride (HgCl2)--as illustrated by proteinuria and by a drop in the glomerular filtration rate (GFR) measured by creatinine clearance test (CCT)--was investigated in Wistar rats. HgCl2, 150 or 250 micrograms/100 g BW per day was injected intraperitoneally three times a week for 2 weeks. Both groups showed a significant degree of proteinuria and urinary TIA. Group B (250 micrograms HgCl2/100 g BW) displayed a greater drop in GFR than group A (150 micrograms HgCl2/100 g BW). The urinary TIA was significantly correlated with proteinuria (group A: r = 0.87, group B: r = 0.84), but it was also significantly inversely correlated with the CCT (A: r = -0.96; B: r = -0.88).

IN CONCLUSION

these results suggest that increased urinary TIA may be involved in and indicative of the pathogenesis of mercuric chloride induced nephrotoxicity.

Neurologic features of chronic Minamata disease (organic mercury poisoning) certified at autopsy

To better understand the neurologic events related to chronic Minamata disease (organic mercury poisoning), we studied data from 77 patients with Minamata disease as certified at autopsies performed from 1976 to 1994 (mean age: 72.3 years). Major neurologic findings included: sensory impairment in 80.5% of the patients which was limited to the extremities in 42.9%. Impairment of lower extremity coordination was present in 35.8% of the patients, constriction of the visual fields in 28.8%, and retrocochlear hearing loss in 15.3%. There was no correlation between the degree of cerebellar incoordination and the methylmercury concentration in the cerebellum. Compared with the classic type of Minamata disease, the incidence of major neurologic findings was markedly decreased. In light of these findings, supplemental examinations including brain computed tomography (CT), magnetic resonance imaging (MRI), short latency somatosensory evoked potential (SSEP), or tremogram may be necessary to clinically diagnose Minamata disease, especially in atypical or mild cases.

MR findings in seven patients with organic mercury poisoning (Minamata disease)

PURPOSE

To study the long-term MR findings in seven patients with Minamata disease.

METHODS

All patients examined were affected after eating daily considerable amounts of the methylmercury-contaminated seafoods from 1955 through 1958 and showed typical neurologic findings. T1- and T2-weighted images were obtained in axial, coronal, and sagittal sections.

RESULTS

The visual cortex, the cerebellar vermis and hemispheres, and the postcentral cortex were significantly atrophic. The visual cortex was slightly hypointense on T1-weighted images and hyperintense on T2-weighted images, probably representing the pathologic changes of status spongiosus.

CONCLUSION

MR demonstrated the lesions, located in the calcarine area, cerebellum, and postcentral gyri, which are probably related to three of the characteristic manifestations of this disease: the constriction of the visual fields, ataxia, and sensory disturbance, respectively.

Methylmercury poisoning: long-term clinical, radiological, toxicological, and pathological studies of an affected family

For 3 months in 1969 a family in the United States that included a pregnant mother consumed pork containing methylmercury. Children, aged 20, 13, and 8 years and a neonate, developed severe neurological signs. Twenty-two years later, the 2 oldest had cortical blindness or constricted visual fields, diminished hand proprioception, choreoathetosis, and attentional deficits. Magnetic resonance images showed tissue loss in the calcarine and parietal cortices and cerebellar folia. The youngest had quadriplegia, blindness, and severe mental retardation until their deaths. The brain of the 8-year-old who died at age 30 showed cortical atrophy, neuronal loss, and gliosis, most pronounced in the paracentral and parietooccipital regions. The total mercury level in formalin-fixed, left occipital cortex was 1,974 ng/gm as measured by atomic absorption. Regional brain mercury levels correlated with extent of brain damage. A control patient had 38.5 ng of mercury/gm in the occipital cortex. Systemic organs in the patient and a control subject had comparable mercury levels. In mercury-intoxicated rats, we found that only 5 to 10% of total brain mercury was lost by formalin fixation. Brain inorganic mercury in the patient ranged from 82 to 100%. Since inorganic mercury crosses the blood-brain barrier poorly, biotransformation of methyl to inorganic mercury may have occurred after methylmercury crossed the blood-brain barrier, accounting for its persistence in brain and causing part of the brain damage.

Mercury and multiple sclerosis

It has occasionally been claimed that multiple sclerosis (MS) may be due to a chronic mercury intoxication, e.g. from mercury liberated from dental fillings. Therefore, the present communication compares the mercury content assayed by neutron activation in 8 macroscopically normal areas (frontal lobe) of MS autopsy brains with those of 8 control samples. No significant differences could be traced between the two groups concerning total mercury. However, the lipid-soluble mercury (preferably methyl mercury) expressed per cell unit (DNA) was found significantly decreased in MS. These data may be explained either by a wash-out of lipid soluble mercury due to break-down of the blood-brain barrier in MS or to abnormalities in methylation processes probably related to the vitamin B12 metabolism in MS.

Mechanisms of kidney cell injury from metals

The most environmentally abundant toxic metals/metalloids (arsenic, cadmium, lead, and mercury) are each known to produce cell injury in the kidney but the molecular mechanisms underlying these events are now being elucidated. It is clear that the nephrotoxicity of these agents is due, in part, to the fact that urinary elimination is a major route of excretion from the body. The role(s) of molecular factors such as metal-binding proteins, inclusion bodies, and cell-specific receptorlike proteins that appear to influence renal tubule cell expression, have attracted increased interest as determinants that modulate cell populations as special risk for toxicity and renal cancer. The future of mechanistic toxicology studies with regard to how and why only certain renal cell populations become targets for toxicity from these metals/metalloids and other less common inorganic nephrotoxicants must focus on the molecular handling of these agents by target cell populations.

[The aging of central nervous system in methylmercury intoxication in Niigata, Japan--quantitative investigation of neurofibrillary tangles and senile plaques]

In order to elucidate the progression of aging process in the brains of methylmercury intoxication in humans, neurofibrillary tangles (NFT) and senile plaques (SP) were examined quantitatively in the temporal lobe and calcarine cortex of 16 patients with methylmercury intoxication and 12 control subjects by using tau and beta-peptide immunostained preparations. The numbers of NFT and SP in the patients of methylmercury intoxication were almost equal to those in control subjects, and statistically there is no significant difference. The findings indicate that the methylmercury intoxication in humans does not induce or exacerbate the NFT or SP forming disease process at least in these regions in the brain.

Interaction of spironolactone with mercury. A possible molecular mechanism

The protective activity of spironolactone (CAS 52-01-7) against mercuric acetate intoxication and the action of a spironolactone-mercuric acetate complex were studied on female Sprague-Dawley rats. Spironolactone was given 30 min after the toxic agent. It was found that spironolactone reversed the toxic effects of mercury, the mercury-spironolactone complex was much less toxic than mercuric acetate and its toxicity disappeared with the administration of spironolactone. A molecular mechanism for the protective action of spironolactone against mercury intoxication is proposed. The presence of both the steroidal skeleton and the thioacetyl group in the same molecule is necessary for the protection against mercury intoxication.

A fetal type of Minamata disease. An autopsy case report with special reference to the nervous system

Our knowledge concerning the pathology of fetal cases of human Minamata disease (methylmercury poisoning) is relatively limited. We report here a case with description of the distribution of mercury in the systemic organs, and the ultrastructural changes of the nervous system after a survival of 29 yr. The patient was a female born in 1957, with a body wt of 3000 g, who died in 1987. She carried a diagnosis of cerebral palsy, and had a convulsion at age 3 yr. Mercury levels in her mother's hair were 101 micrograms/g at the time of examination in 1959. At autopsy, the body measured 43 cm and weighed 23 kg. The brain weighed 920 g and showed marked cerebral atrophy, mild neuronal loss in the calcarine, postcentral and precentral cortices, cerebellar atrophy, and segmental demyelination of peripheral nerves. Mercury granules were present in the brain, kidney, and liver. Ultrastructural examination of the calcarine, post- and precentral cortices, and cerebellar cortices, showed severe atrophy of nerve cells, with a decrease in rough ER and an increase in nuclear chromatin and preservation of mitochondria. Autophagosomes were increased in number. In addition, high electron density, globular and dense bodies, measuring 0.3-1.8 microns in diameter, were found, surrounded by limited membrane, within both cerebral and cerebellar neurons. In the cellebellum, synapses were well-preserved.

[Morphological and toxicological findings after intravenous injection of metallic mercury]

At the autopsy of a 25-year-old man who had died from combined morphine and cocaine intoxication, depositions of metallic mercury were incidentally found in the myocardium of the right ventricular septum and posterior wall. Deposits, toxicologically identified as mercury, were also found radiologically and histologically in the lungs. All these deposits were probably the result of intravenous injections of mercury many months previously, as is known to be done occasionally by addicts. Judging by the histological picture the greatest proportion of the mercury collected in the right ventricular cavity after injection, a smaller amount by embolization in the small pulmonary arteries. The mercury spheres which came to lie in the right ventricle then penetrated into the myocardium, moving outward and causing a chronic and partly transmural inflammatory response.

Inorganic mercury transport in the proximal tubule of the rabbit

Inorganic mercury transport was studied in the S1, S2, and S3 segments of the isolated perfused proximal tubule of the rabbit. The concentration of mercury in the perfusate was 18.4 microM. At this concentration all three segments of the proximal tubule underwent degenerative changes that proceeded to cellular necrosis at the end of the tubule which was attached to the perfusion pipet. This pathological process progressed along the tubule for approximately 200 microns. The remainder of the tubule, to the collection pipette, remained intact and free of any pathological changes. In examining the transport of mercury under these condition, it was found that, on average, the S1, S2, and S3 segments all removed inorganic mercury from the luminal fluid at approximately 140 fmol min-1 mm-1. The transport of mercury, as measured by the appearance of 203Hg in the bathing solution, was 80% lower than the removal of 203Hg from the luminal fluid. The mercury appearing in the bath could be accounted for by passive leakage through the necrotic portion of the tubule in the S1 and S2 segments, but not in the S3 segment. Leakage could account for only 16.2% of the transepithelial movement of inorganic mercury in the S3 segment. Inorganic mercury taken up by the tubule (92%) was primarily associated with the structural proteins of the tubular epithelial cells, while very little (8%) was found in the tubular extract. The toxicity of inorganic mercury was determined by titration. Perfusion with 1 microM inorganic mercury produced necrosis. The pathological features appeared to be the same as those resulting with 18.5 microM inorganic mercury.(ABSTRACT TRUNCATED AT 250 WORDS)

The neurotoxicology and pathology of organomercury, organolead, and organotin

The toxicities of many metals, such as mercury and lead, are known to man since the dawn of civilization. Organic compounds of some heavy metals are known to have a particular toxic impact on the central nervous system. Organomercury, particularly alkyl-mercuric compounds (e.g. methylmercury), has a selective effect on the granule cells of the cerebellum, the nerve cells of the calcarine cortex, and the sensory neurons in the dorsal root ganglia. The well known Minamata Bay disease is the result of a massive epidemic episode of human exposure to alkylmercury contaminated food sources. Mental retardation and other developmental defects are also known to be a consequence of exposure to this toxic metal. Organic lead compounds have been employed as gasoline additives and in other industrial purposes. Unlike its inorganic counterpart, organolead compounds have a more prominent impact on the central nervous system. Pathological changes of the brain stem neurons have been described. Organotin compounds have been used in plastic industries and as agricultural chemicals. Both trimethyl and triethyl tin compounds are found to be extremely neurotoxic. Despite the similarity of their chemical structures, trimethyl and triethyl tins have a diversely different toxic property and effects. While triethyl tin is myelinotoxic, producing edematous and vacuolar changes in the central myelin, trimethyl tin is neurotoxic, producing prominent toxic changes in the neurons of the limbic system (hippocampus, entorhinal cortex, etc.). The factors which determine the specificity and selectivity of the neurotoxic impacts by various organometals are still unknown. In view that most of the organometals are still widely employed by many countries for industrial and for agricultural purposes, caution must be made for their proper handling and disposure to avoid undesirable exposures to workers and environmental contamination of water sources and food-chain for the common public. Since organometals are difficult to eliminate from the central nervous system, injuries usually lead to permanent neurological deficits, such tragedies are frequently long lasting and create not only a medical problem, but also a social economical problem for the society.

[Lichen ruber exanthematicus et pigmentosus in mercury poisoning. A contribution to individual pathology in occupational medicine]

We report on a 21-year-old man professionally exposed to mercury, who developed lichen planus. This case must be regarded as a dispositional reaction and is in Germany entitled to indemnification in terms of a "quasi-occupational disease". The clinical signs and the probably non-allergic pathomechanism are comparable with those of lichen planus induced by gold. In diseases due to occupational intoxication, we face an individual disposition regarding the degree of clinical symptoms, which has to underly any expert opinion on indemnity.

Accumulation of mercury in brainstem nuclei of mice after retrograde axonal transport

Adult mice were injected intramuscularly in the region of the vibrissae muscles on the left side of the nose with a small volume of mercuric chloride dissolved in distilled water. The animals were killed after 1-6 weeks and fixed by whole-body perfusion. Frozen sections were taken from different levels of the brain stem and from the kidney. The sections were subjected to silver acetate autometallography for visualization of mercury. Mercury was found to accumulate in neurones of the facial nerve nuclei, of the motor trigeminal nuclei and of the trigeminal mesencephalic nuclei of the brain stem, after retrograde axonal transport. Mercury was also demonstrated in proximal tubular cells of the kidney. The mechanism for uptake of mercury at the neuromuscular junctions, and the fate of mercury within neurones are analysed. The possible significance of retrograde metal transport for the development of motor neurone disease is discussed.

Mercury pigmentation and high mercury levels from the use of a cosmetic cream

A 42-year-old woman presented with facial mercury pigmentation, raised levels of mercury in the blood and urine and possible neuropsychiatric toxicity after the topical application of 17.5% mercuric ammonium chloride. The patient purchased a mercury-containing cream without prescription from Victorian pharmacies for many years to lighten her complexion. She was unaware of any health risk. No warning appears on the package or insert of the cream she used. Health workers, particularly pharmacists and medical practitioners, should be aware that over-the-counter mercury-containing creams may raise the concentrations of mercury in the blood and urine to potentially toxic levels. A warning on the package should be considered and use of the cream restricted.

Acute alterations of tissue Ca++ and lethal tubular cell injury during HgCl2 nephrotoxicity in the rat

The relationship between acute alterations of tissue Ca++ and the development of acute renal failure and lethal renal tubular cell injury in the kidney was studied. Nephrotoxicity was induced by HgCl2, and its course was modified by prior saline drinking. Both a semiquantitative scale measuring the extent of lethal tubule cell injury and a computerized assessment of numbers of nuclei in Feulgen stained sections of cortex were used for morphologic analysis. The 2 methods agreed very closely with each other, indicating the utility of an automated computerized approach as a rapid, quantitative adjunct for the assessment of lethal cell injury in the kidney. Increases of blood urea nitrogen during 12-24 hr after HgCl2 were associated with increasing extent of lethal cell injury in both saline and water drinking rats. Striking progressive increases of renal cortical Ca++ developed. In both water and saline drinking rats, the increases in tissue Ca++ were significantly associated with increasing blood urea nitrogen levels and extent of lethal cell injury as determined morphologically. However, similar degrees of increased blood urea nitrogen and extensive lethal cell injury were accompanied by substantially lower tissue Ca++ levels in saline drinking rats than in water drinking rats, indicating an independent effect of saline drinking to ameliorate the increases in tissue Ca++ occurring during lethal cell injury in this model. These data provide further insight into the relationship between structural and functional changes during HgCl2 nephrotoxicity and establish the utility of an automated computerized morphometric method for assessing the extent of lethal cell injury.

Persistent mercury in nerve cells 16 years after metallic mercury poisoning

A male subject, after exposure to mercury metal at work in 1968, developed classical signs of mercurialism from which he made a slow clinical recovery. He subsequently developed psychoneurotic symptoms and became an alcoholic; he never returned to work and died in 1984. No histological changes relevant to mercury intoxication were found in the brain, but staining by Danscher & Schroeder's method for mercury showed many positively staining lysosomal dense bodies in a large proportion of nerve cells, and the presence of mercury was confirmed by elemental X-ray analysis. The mercury content of the brain was increased, much of it being present in colloidal form.